I also just remembered I have another friend with years of good history on Facebook, who got hacked in some way several months ago, and they have NEVER been able to restore her account. People are getting away with this shinola every day, and you have no recourse.
As for the app... I hate most "apps", of just about anything, and the only time the FB one gets used is when something directs me to something that opens it by default. And that's a rare occurrence. I go for the desktop versions of everything I can, all the time.